A number of food processing methods comprise the steps of heating to an elevated temperature to effect cooking and/or sterilisation and then cooling prior to aseptic packaging. For any particular foodstuff, the maximum target temperature to be attained by heating, and generally held for a short period to achieve sterilisation, is quite critical, as it affects the quality of the finished product. Especially in the case of a solid foodstuff, it has proved very difficult with known methods to achieve the target temperature uniformly throughout the mass of the foodstuff, with the result that localised overcooking or undercooking occurs and/or the quality of the finished product is impaired.